Why the difference between these two minority groups?
David Bernstein raises this question and addresses it over at The Volokh Conspiracy:
Why the difference? I think it has its roots in the different historical experiences of the two groups. Jews, being a minority people in exile, often were only able to protect themselves by establishing relationships with those in power. When the people turned against those in power, they turned against their Jewish advisors and allies as well, and by extension against the Jews. And when Jews were emancipated and became involved in political movements, ranging from liberalism to Communism, their ideological adversaries rarely hesitated to stir up opposition by focusing on Jewish leaders of the movement, resulting, for example, in the murder of tens of thousands of Jews by the White Russians during the Russian revolutionary upheaval. Even today in the U.S., anti-Jewish prejudice manifests itself in complaints about disproportionate Jewish political power, as witnessed by the oft-heard claim that Jewish neoconservatives manipulated the Bush Administration into war with Iraq.This is not something that was limited to Europe. Mitchell Bard writes about the same thing happening in the Muslim world as well:
When Jews were perceived as having achieved too comfortable a position in Islamic society, anti-Semitism would surface, often with devastating results: On December 30, 1066, Joseph HaNagid, the Jewish vizier of Granada, Spain, was crucified by an Arab mob that proceeded to raze the Jewish quarter of the city and slaughter its 5,000 inhabitants. The riot was incited by Muslim preachers who had angrily objected to what they saw as inordinate Jewish political power.On the other hand, historically African Americans have not had to deal with the same situation.
By contrast, African Americans have suffered in large part because of their lack of political power. With 12% or so of the population and deep historic roots in American life, African Americans are less worried about being seen as outside interlopers seizing power from "real Americans", and more worried about the very real consequences they have suffered from being excluded from political power.Jews have just been burned--at times, literally--too many times over history. After a while, it makes an impression.